The Supreme Court is considering whether “mixed-motive” retaliation claims are permissible under Title VII of the Civil Rights Act of 1964. In University of Texas Southwestern Medical Center v. Nassar, the court will decide whether a plaintiff claiming retaliation must prove that the employer’s retaliatory motive was the “but-for” cause of an adverse employment action, or whether the plaintiff can prevail by demonstrating that retaliation was one of several motivating factors. The questioning during last week’s oral argument suggests that the court is closely divided but may lean toward applying the more demanding causation standard.

In Price Waterhouse v. Hopkins, the Supreme Court adopted a burden-shifting framework for proving discrimination under Title VII. It held that a plaintiff alleging discrimination could satisfy his or her initial burden of proof by showing that the discrimination was “a motivating factor” in an adverse employment decision. The burden then shifted to the employer, which could avoid liability by proving that it would have taken the same action regardless of the discriminatory motive.

In 1991, Congress amended Title VII to provide for “mixed-motive” liability. The amendment states that “an unlawful employment practice is established when the complaining party demonstrates that race, color, religion, sex, or national origin was a motivating factor for any employment practice, even though other factors also motivated the practice.” It further provides that the employer may avoid paying damages or back or front pay—but remains liable for declaratory relief, injunctive relief and attorney’s fees—if it proves that it would have made the same decision absent the improper motive. Because Section 2000e-2(m) does not expressly refer to Title VII’s separate provision prohibiting retaliation, it is unclear whether it applies to retaliation claims.

In Gross v. FBL Financial Services, Inc., the Supreme Court held in 2009 that plaintiffs suing under the Age Discrimination in Employment Act (ADEA) must prove “that age was the ‘but–for’ cause of the challenged employer decision.”The court reasoned in part that in 1991 Congress expressly approved mixed-motive discrimination claims under Title VII, but made no similar amendment to the ADEA—raising the inference that Congress did not wish to allow mixed-motive claims under the ADEA. The petitioner in Nassar argues that a similar negative inference precludes mixed-motive retaliation claims under Title VII. Nassar and the U.S. disagree. They point out that by the time Congress amended Title VII in 1991, the Supreme Court had already interpreted general anti-discrimination provisions in other statutes to prohibit retaliation. They contend that the references in Section 2000e-2(m) to discrimination based on “race, color, religion, sex, or national origin” thus should be read to include retaliation.

At last week’s oral argument, Justices Kagan, Sotomayor and Ginsburg expressed skepticism that Congress meant to adopt different causation standards for discrimination and retaliation under Title VII. But Justice Scalia’s questions suggested that he construes the 1991 amendments to exclude retaliation claims. Chief Justice Roberts appeared sympathetic to that view, noting that “it would have been so easy” for Congress to refer to retaliation in Section 2000e-2(m) but that it did not do so. Justice Alito observed that “the motivating factor analysis may create special problems… in the retaliation context,” while Justice Kennedy asked whether there were reasons for the court to be “very careful about the causation standard” when addressing retaliation.

Although it is impossible to predict the outcome with certainty, it appears likely that the majority will vote to apply a “but-for” causation standard to retaliation claims under Title VII. A decision is expected by June.